The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Recently, increase of oil price triggered a more competition than before to enhance fuel efficiency of a vehicle.
In this sense, research on an automatic transmission has been performed to simultaneously provide better drivability and fuel consumption by achieving more shift stages.
In order to achieve more shift stages for an automatic transmission, the number of parts is typically increased. This negatively affects installability, production cost, weight and/or power flow efficiency.
An automatic transmission providing eight or more shift-stages may easily become lengthy due to increased components, thereby deteriorating installability.
In this regard, disposing planetary gear sets in parallel or employing dog clutches instead of wet-type control elements is sometimes attempted. However, we have discovered that such an arrangement may not be widely applicable, and using dog clutches may easily deteriorate shift-feeling.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.